1. Field of the Invention
The present invention relates to an extensible exercise golf club for training golfers and more particularly, to an exercise golf club which includes a plurality of telescopic interlocking tubular shaft lengths containing a vacuum space disposed therein for causing the telescoped shaft lengths to extend from a collapsed position to a fully extended position and then to collapse from the extended position to a fully collapsed position as a result of the force generated by the vacuum space. Thus, beginning golfers can learn to swing a golf club very easily with very little effort, thus effectively reducing the training period.
2. Description of the Prior Art
Several types of collapsible golf clubs are known in the art. For example, such golf clubs include those which possess adjustable shaft lengths; means for varying the grip of golf clubs axially collapsible shafts, and the like. However, such collapsible golf clubs suffer from many problems. For example, it is difficult for a beginning golfer to timely hit a golf ball using such golf clubs and to properly control the power transferred from the legs of the golfer to a golf club head. Such golf clubs are described in U.S. Pat. No. 2,107,983 to Hamilton, U.S. Pat. No. 2,214,079 to Horton, U.S. Pat. No. 2,772,887 to Blake, U.S. Pat. No. 3,070,370 to Steiner, U.S. Pat. No. 3,102,726 to Barrett, U.S. Pat. No. 3,214,170 to Warnock, U.S. Pat. No. 3,524,646 to Wheeler, U.S. Pat. No. 3,528,660 to Kategian, U.S. Pat. No. 3,539,185 to Andis, U.S. Pat. No. 3,663,019 to Palotsee, U.S. Pat. No. 3,829,092 to Arkin, U.S. Pat. No. 3,840,231 to Moore, U.S. Pat. No. 4,343,473 to Laursen, U.S. Pat. No. 4,674,747 to Mazzocco et al.
In order to avoid such problems, U.S. Pat. No. 4,931,661, issued to the present inventor, describes an extensible exercise golf club including a golf club shaft comprising a plurality of telescopic tubular members which telescopically fit into each other for slidably extending from a telescopically collapsed position to a telescopically extended position. Channel and rail members are disposed alternately on the inner and outer surfaces of adjacent telescopic tubular members, whereby the rail member of one tubular member engages the channel member of an adjacent tubular member for interlocking the adjacent telescopic tubular members together. Thus, upon swinging the golf club, the club shaft member of the golf club is guided by the engagement of the rail members within the channel members whereby the twisting of adjacent shaft members is effectively prevented.
However, this extensible exercise golf club is complicated in structure and expensive to manufacture. Furthermore, in order to collapse the extended telescopic tubular shaft members, the golfer has to utilize force to push the tubular shaft members, which takes time in its operation. Sometimes, if the channel and rail members become broken, the extensible exercise golf club cannot be used and thus it becomes uneconomical.